The answer is A it's the action of purifying water
The correct answer is letter A
The answer is written on the pic I sent you with this
Glucose is virtually the sole fuel for the human brain, except during prolonged starvation. The brain lacks fuel stores, thus requires a continuous supply of glucose. It consumes about 120 g daily which corresponds to an energy input of 420 kcal (1760 KJ), accounting for some 60% of the utilization of glucose by the whole body in the resting state.